1. Field of the Invention
Embodiments of the present disclosure relate to liquid crystal display technology, and more particularly to a backlight driving circuit and the liquid crystal display with the same.
2. Discussion of the Related Art
Boost converters or set-up converters are usually adopted in backlight driving circuits to provide direct current (DC) voltage to Light Emitting Diodes (LEDs).
As shown in FIG. 1, the boost converter indicated by the dashed lines includes a first inductance L1, a second diode D10, a resistor R10, a capacitor C1, and a Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET) Q2. The driving chip provides pulse-width-modulated (PWM) signals to control the MOSFET Q2. Before the MOSFET Q2 is turn on, the capacitor C1 supplies power to the LED light bar, and a source of the second MOSFET Q2 is grounded via the resistor R10.
In addition, the boost converter further includes a current setting circuit. The current setting circuit includes a triode Q3, and resistors R1 and R2 connected in parallel are between a collector of the triode Q3 and the ground. The resistance value R of the resistors R1 and R2 is given by:R=(R1*R2)/(R1+R2)
It can be seen that when the resistance value of R1 and R2 are different, the precision of the resistor may affect the resistance R when the resistor has a reduced resistance value. As such, the current precision is also affected. If the precision of each of the resistor is a %, when the resistance of one resistor is reduced for a %, the precision of the current may be reduced for an approximate amount equaling to a %.